IN-VITRO PRODUCTION OF SHEEP EMBRYOS USING LAPAROSCOPIC FOLLICULOCENTESIS - ALTERNATIVE GONADOTROPIN TREATMENTS FOR STIMULATION OF OOCYTE DONORS

Three different gonadotrophin regimens for the stimulation of donors f or laparoscopic folliculocentesis were tested in a total of 142 ewes. The recovered oocytes were subjected to in vitro maturation, fertiliza tion, and culture (IVM/IVF/IVC) for 7 d using standard procedures for sheep. The estrous cycles of all ewes were synchronized using intravag inal sponges containing 60 mg of medroxyprogesterone acetate (MPA) ins erted for 14 d. In Experiment 1, all ewes were superovulated with a to tal dose of 125 IU FSH and 125 IU LH. One-half of the ewes received th e gonadotrophin treatment in 4 decreasing doses at 12-h intervals star ting 48 h before follicle aspiration (Control), while the other half r eceived the total dose in a single injection at -24 h before collectio n (Oneshot). There were no significant differences between treatments for recovery rate (81.6+/-5.3 vs 77.4+/-10.3), cleavage rate (60.6+/-2 0.8 vs 61.4+/-23.4), or normal development to the blastocyst stage (20 .8+/-18.2 vs 13.1+/-10.3). However, a higher percentage of ewes produc ed at least 1 normal blastocyst in the Control group (56.4 vs 31.6%; P <0.05). In Experiment 2, the control regimen was repeated in half of t he ewes, while the remainder were treated with half of the FSH total d ose plus 500 IU eCG in a single injection at -24 h before oocyte colle ction (Oneshot-eCG). The recovery rate (80.9+/-5.6 vs 73.3+/-15.3), cl eavage rate (76.8+/-19.9 vs 79.7+/-22.6), normal development to blasto cysts (19.2+/-15.3 vs 23.3+/-10.7), and percentage of ewes producing a t least 1 normal blastocyst (55.9 vs 51.6%) did not differ between tre atments. The large variability observed between ewes in the production of normal blastocysts is comparable to that observed with standard MO ET procedures, in which a proportion of donors fail to produce good em bryos. With the in vitro procedures described here, we were able to pr oduce normal embryos from more than half of the treated ewes, indicati ng that the technology is useful for the multiplication of genetically valuable animals affected by temporary or irreversible infertility.